This invention relates in general to apparatus and methods for feeding discrete objects to a processing machine. More specifically, it relates to a system and method that automatically feeds integrated circuits stored in hollow tubes to a test handler/sorter.
In the manufacture of dual-in-line-packaged (DIP) integrated circuits (IC's) the circuits are usually stored in an end-to-end array in a hollow plastic tube. The tube has a general U-shaped cross section to accommodate the two rows of leads extending down from both sides of the IC. The IC's slide freely in the tube and one or both ends of the tube can have stop pins inserted to hold the IC's in the tube. After their manufacture or prior to their use as a component in electronic equipment, IC's are tested and sorted based on the results of the test. Modern testing and sorting machines capable of processing IC's at a throughput rate in excess of 5,000 devices per hour are manufactured and sold by Daymarc Corporation, the assignee of this application, under its Model Nos. 1157 HL and 757. With either machine one stop pin is removed from the tube to allow the discharge of IC's from the tube to the tester/sorter. The present invention is particularly adapted for use in combination with the new Model 757 test handler/sorter where the IC's are fed to a storage unit that is inclined from the horizontal.
Production economics require that the tester/sorter operate at high rates. It is therefore necessary that the IC's be fed to the tester at a corresponding high rate, and with a high degree of reliability. One prior art feeding arrangement is the straightforward expedient of manually loading tubes onto a mechanism that feeds the IC's to a processing path (in one instance, a rotating table that carries the IC's in a spaced relationship at its periphery). Other known systems use "turrets" that carry several lines of IC's arrayed about a common axis of rotation. The IC's are manually loaded into the turret at one point from a tube and discharged at another point to a test handler/sorter. Manual systems are both slow and require an attendant to continuously feed tubes loaded with IC's to the feed mechanism. Another problem with vertical feed systems (where the tube is oriented vertically during the unloading process) is that the IC's within the tubes can assume different angular orientations with respect to the longitudinal axis of the tube. This can damage the IC's.
Various automated feed systems have been tried. Some systems designed in Japan store the tubes horizontally with one end of each tube open. One difficulty with these systems is that IC's can escape from the tube and additional care is required in handling them. Conveyors have also been used to advance tubes stacked side by side in an automated feed system. However, heretofore the conveyors have always transported the tubes while they are substantially vertical. Also, the tubes have always been open at their lower end so that the discharge could use a vertical gravity feed. Another significant limitation of prior art conveyor systems is that they require discrete fixtures to define locations on the conveyor. The tube must then be loaded into the fixtures and then removed from them. Another disadvantage is that fixtures are typically sized to accept one type of tube, whereas tubes have different standard dimensions to accommodate different standard IC's.
It is therefore a principal object of this invention to provide an automatic loading system and process for tubes of IC's of varying size that is reliable, operates at a high speed, and requires a low level of operator attention.
Another object is to provide a system with the foregoing advantages that does not require large amounts of hardware.
Yet another object is to provide a system, with the foregoing advantages that tolerates a variety or orientations of the tubes when they are initially placed in the system.
A further object is to provide a loading system with the foregoing advantages that also has an expandable tube-holding capacity.
Still another object is to provide a loading system where all of the operational components are readily accessible.